Apparatus for photographing well core samples



March 12,1968

R. E. JENKINS ET AL APPARATUS FOR PHOTOGRAPHING WELL CORE SAMPLES FiledFeb. 1, 1966 6.? 6, 2 60 nno/umunmuucJ/ununfi I /I8 l'8 I 1- M -1--TIIXW35 T" ,5 i' -5 "*7 7??? 18 WELL No----. 9 l0 wu.uo-- C 9 IO WELLN 5magma-.- 50 64 LOOATION-.-.- W50 LOGATI UUUUUUUUUUUUUUDUUUDU INVENTORSRALPH E. JENKINS United States Patent 3,373,440 APPARATUS FORPHOTOGRAPHING WELL CORE SAMPLES Ralph E. Jenkins, Irving, and Harold T.Barnaby, Buncanville, Tex., assignors to Core Laboratories, Inc.,Dallas, Tex.

Filed Feb. 1, 1966, Ser. No. 524,169 3 Claims. (Cl. 346--107) ABSTRACT@F THE DISCLOSURE Well core samples are photographed by arranging themon a conveyor end-to-end in a string in the same order they occupiedprior to removal from the Well borehole, moving the conveyorcontinuously While actuating the shutter of a camera directed at thestring by automatic means coupled to the conveyor so that the shutter isactuated at uniform intervals during which the string moves a distanceequal to the length of the field of view of the camera, and advancingthe film between successive exposures a distance substantially equal tothe length of the film exposed on each such actuation to form acontinuous strip photograph of the string.

This invention relates to strip photographs of core samples removed fromwell boreholes and to a method of making such photographs.

In the drilling of oil and gas wells, for example, it is customarypractice, when the drilling bit approaches an underground formationwhich may possibly contain oil or gas, to substitute a core bit and corebarrel and take core samples of the strata traversed during the ensuingdrilling. These samples are brought to the top of the well and analyzedfor such characteristics as lithology, porosity, permeability, and oiland water saturation, which data form the most reliable means fordetermining whether the formations from which the core samples weretaken are capable of producing oil or gas on a commercial basis.

While it is normally desirable to have such core analyses performed asquickly as possible after removal of the cores from the borehole, inorder that the data obtained may be utilized in determining Whetherfurther drilling is necessary or whether the well may be completed forproduction at the horizon already reached, it is almost invariablydesired to keep the core available for subsequent inspection andanalysis, perhaps even years after the drilling of the well. Thus, mostcompanies in the petroleum industry provide extensive storage facilitiesfor maintaining and preserving the cores recovered from wells drilled byor for them. Either the geologists or other company personnel desiringto examine the core samples must go to where the core is, or the coremust be brought to them, in either case entailing appreciable time andexpense. This also imposes a severe limitation on the amount of corewhich can be examined by the companys most skilled geologists, and makesit necessary to rely on their less experienced subordinates forexamination of much of the core. In many instances, only a visualinspection of the core samples is required, in which case photographs,particularly color photographs, of the core samples would serve as well,thereby obviating the time and expense involved in examination of thecore itself, and permitting much more or even all of the core to beexamined by the companys top geologists.

In general terms, the present invention supplies this need by providinga strip photograph comprising a series of closely spaced framesportraying successive, substantially contiguous and non-overlappingsections of the string of core samples appearing in the same relativepositions which they occupied prior to removal from the borehole, sothat the photograph is, in practical effect, an elongated, substantiallycontinuous picture of the core. Preferably, but not necessarily, eachframe may represent one foot of length of the string of core samples andthe frames may show numerals corresponding to the reported depths infeet from which the respective one-foot sections of the core were taken.

According to the method of the present invention, this photograph ismade by arranging the core samples endto-end in the same relativepositions which they occupied prior to removal from the Well boreholeand moving the string of core samples past a fixed camera directed atthe core samples While actuating the shutter of the camera to expose thefilm therein at intervals corresponding to uniform distances of movementof the string, the camera being so spaced from the core samples and itslens having such focal length that the frames thus exposed portraysubstantially contiguous and non-overlapping sections of the string, andwith the film being advanced between such successive exposures byuniform distance approximately equal to the stripwise length of theframes. The optional depth indicia are placed on the film strip byarranging a mechanical counter adjacent said string of core samples inthe field of view of said camera, said counter being coupled to theconveyor which moves the string of core samples past the camera, so thatthe counter is indexed one digit for each foot of movement of thestring, with the counter being preset so that when the first section ofthe string is photographed, the dial of the counter shows numeralscorresponding to the reported depth in feet from which this section wastaken.

Advantageously, but not necessarily, the core samples may be conveyed bythe apparatus disclosed in US. Patent No. 3,025,398, and thusphotographed at the time of making the radiation log disclosed in thatpatent,

thereby obviating the need for additional handling of the core.

The film may be viewed, for example, by the use of a compact strip-filmprojector, which projects images against either a screen or a blankwall, with the film being advanced manually so that the image of anyselected interval of core may be viewed for as long as desired. Theconsiderable enlargement of the image produced by projection affordssome of the advantages of a microscopic examination of the core, whilepermitting the entire width of the core to be examined simultaneouslyand to be compared with adjacent sections of the core.

In the drawings:

FIGURE 1 is a somewhat diagrammatic perspective view showing a method ofphotographing core samples within the scope of the present invention.

FIGURE 2 is an enlarged, fragmentary plan view of film strip embodyingfeatures of the present invention.

The aforementioned US. Patent No. 3,025,398 discloses a method ofdeterming the wireline-measured depth of the formation from which coresamples were taken from a well borehole which includes the steps ofplacing the core samples in line in the same sequence as the relativepositions they occupied prior to removal from the borehole and movingthis string of core samples relatively to a radiation sensitive device,while making a graphic record of the intensity of radiation detected bythe device, and correlating this record with a conventional downholeradioactivity log made with a wireline-supported sonde.

Said patent discloses an apparatus for making the surface radiation logof the core samples which includes an endless belt on which the stringof core samples is supported and which is motor-driven to move thestring of core samples continuously past a stationary radiationdetector, such as a scintillator. The process of that patent has goneinto widespread commercial use, particularly in what is known as hardrock country, such as the Permian Basin. Thus, the apparatus is alreadyavailable in many areas.

In FIGURE 1, the string of core samples C are shown supported upon theendless belt of such an apparatus, which is more fully described in saidUS. Patent No. 3,025,398. The belt 10 is supported at each end upondrums, one of which is shown at 12 and which is driven by a pulley 14through a belt 16, which in turn is driven by an electric motor (notshown). The core samples C, supported upon the upper span of the belt Itare guided laterally between adjustable side rails 18, and are movedcontinuously through a lead-shielded tunnel containing a scintillationdetector which, through appropriate electrical circuits in the cabinet22, drives a strip recorder 24 to plot a graph of the level of radiationdetected by the scintillator.

Mounted directly above the conveyor belt 10 in position to photographthe core samples after they emerge from the tunnel 20 is a cameragenerally designated 30, adjustably supported on a crossarm 32 securedat the upper end of a vertical post 34. Also supported on the verticalpost 34 are a pair of stroboscopic lights 36 secured at the ends ofadjustable horizontal arms 38 projecting from a collar an encircling thepost 34-. The stroboscopic lights 36 are arranged to illuminate thesection of core being photographed by the camera for a brief instantduring the interval the shutter of the camera 3t) is open. The speed ofthe film and the f number of the lens and shutter of the camera 30 aresuch that, in ordinary room lighting, no appreciable exposure of thefilm takes place during the brief interval the shutter is open exceptduring that instant when the stroboscopic lights 36 are flashed. Theduration of the flash is so brief that the movement of the core samplesC on the continuously driven conveyor belt 10 is effectively stopped, sothat the image of the core on the film in the camera 30 is substantiallyfree of blurring.

The camera 30 is of the electrically operated type wherein electricalimpulses cause opening of the shutter to expose the film, followedautomatically by motor-driven advance of the film preparatory for thenext exposure. The camera 30 is controlled by means of an electricalswitch 42 whose plunger 42a is actuated by a cam 44 fixed at the end ofa shaft 46 driven by a wheel 48 which frictionally engages the uppersurface of the conveyor belt 10 at a point directly above the highestpoint of the drum 12. The wheel 4-8 has a circumference, for example, ofexactly 1 foot so that it and the cam 44 make one revolution for eachfoot of linear travel of the conveyor belt 10, bringing the high pointof the cam 44 opposite the switch 42 and causing the camera 3% to beactuated to take one photograph for each foot of core sample.

The spacing of the camera 30 from the string of core samples C and thefocal length of its lens are such that each frame exposed on the filmconsists of the image of a section of the string of core samples havinga length exactly equal to the circumference of the cam 44, for example,one foot. The film is advanced between adjacent exposures by a distancesuch that the adjacent exposed frames do not overlap, but either justtouch the adjacent frames or leave a very narrow line of unexposed filmbetween adjacent frames.

Thus, as shown in FIGURE 2, the film strip 60 consists of a series ofsuccessive frames 62 separated by thin spaces 64, with the respectiveframes each portraying substantially contiguous and non-overlappingsections of the string of core samples C, so that the film consistsessentially of an elongated, continuous picture of the string of coresamples.

As shown in FIGURE 1, there may be mounted alongside the string of coresamples C on the conveyor belt ltl, within the field of view of thecamera 30, a mechanical counter 50 having its dial facing the camera.The counter 5b is actuated through a rotary shaft 52 having fixed at itsouter end a miter gear 54 which meshes with another miter gear 56' onthe aforementioned shaft 46. Thus, the shaft 52 makes one revolution foreach foot of movement of the conveyor belt and this causes the dial ofthe counter 50 to be indexed one digit. The counter 50 is preset so thatits dial indicates numerals corresponding to the drillers reported depthof the formation from which the first foot of core samples photographedwere taken. Thus, as the conveyor belt 1t conducts the string of coresamples beneath the camera 30, the dial of the indicator St} isautomatically indexed so that, as shown in FIGURE 2, the successiveframes of the film will show numerals corresponding to the reportedsource depths of the respective sections of core portrayed.

There may be also mounted alongside the string of core samples, withinthe field of view of the camera 3%, a card 59 marked with the wellnumber and location so that each frame of the film will also show thisinformation.

It will therefore be appreciated that the aforementioned and otherdesirable objectives have been achieved. However, it should beemphasized that the particular illustrative embodiments of the inventionwhich are described herein and shown in the accompanying drawings areintended as merely illustrative of the principles of the inventionrather than as restrictive of the scope thereof, which is defined onlyby the appended claims.

We claim:

1. Apparatus for photographing Well core samples comprising an endlessconveyor adapted to support a string of core samples arranged end-to-endin the same order as the relative positions they occupied in the wellbore, means to drive said conveyor continuously in one direction, aphotographic camera arranged above said conveyor and directed downwardlyat said string, the lens of said camera being so spaced from said stringand having such focal length as to expose a predetermined stripwiselength of the film of said camera to the image of a predeterminedinterval of the length of said string upon each actuation of the shutterof said camera, shutter actuating means for actuating the shutter ofsaid camera, said shutter actuating means being coupled to said conveyorto actuate said shutter each time said conveyor and said string move adistance equal to said predetermined interval, and film transport meansin said camera for moving said film a distance approximately equal tosaid predetermined stripwise length of said film upon each actuation ofsaid shutter, whereby to form a substantially continuous stripphotograph of said string.

2. Apparatus for photographing well core samples comprising an endlessconveyor adapted to support a string of core samples arranged end-to-endin the same order as the relative positions they occupied in the wellbore, means to drive said conveyor continuously in one direction, aphotographic camera arranged above said conveyor and downwardly directedat said string, the lens of said camera being so spaced from said stringand having such focal length as to expose a predetermined stripwiselength of the film of said camera to the image of a predeterminedinterval of the length of said string upon each actuation of the shutterof said camera, shutter actuating means for actuating the shutter ofsaid camera, said shutter actuating means being coupled to said conveyorto actuate said shutter each time said conveyor and said string move adistance equal to said predetermined interval, stroboscopic light meansarranged to illuminate the portion of said string in the field of viewof said camera and light energizing means coupled to said conveyor toflash said stroboscopic light means during the interval when saidshutter is open.

3. Appartus for photognaphing well core samples comprising an endlessconveyor adapted to support a string of core samples arranged end-to-endin the same order as the relative positions they occupied in the wellbore, means to drive said conveyor continuously in one direction, aphotographic camera arranged above said conveyor and directed downwardlyat said string, the lens of said camera being so spaced from said stringand having such focal length as to expose a predetermined stripwiselength of the film of said camera to the image an interval of saidstring one foot in length upon each actuation of the shutter of saidcamera, shutter actuating means for actuating the shutter of saidcamera, said shutter actuating means being coupled to said conveyor toactuate said shutter each time said conveyor and said string move adistance of one foot, a mechanical counter positioned in the field ofview of said camera with its dial generally facing said camera, saidcounter being coupled to said conveyor so that it is actuated to indexone digit for each foot of movement of said conveyor and said string,and film transport means in said camera for moving said film a distanceapproximately equal to References Cited UNITED STATES PATENTS 2,361,18310/1944 Eddy 8824 2,422,852 6/ 1947 Ratcliffe 75-153 2,425,929 8/1947Foster 8824 3,101,232 8/ 1963 McLaron et a1. 346-l0 7 RICHARD B.WILKINSON, Primary Examiner.

I. W. HARTARY, Assistant Examiner.

